Aggregate Planning. Planning Process. Aggregate. Capacity options. Demand options. Five questions of aggregate planning. Scheduling Decisions

Transcription

1 Aggregate Planning Planning Process Scheduling Decisions Operations Management Chapter 13 Short range Medium range Long range Chris Schrage OPS 13 2 Aggregate Combining appropriate resources into general or overall terms Disaggregation Breaking up components of aggregate plan into detailed aspects Five questions of aggregate planning Should inventories be used to absorb changes in demand during the planning period? Should changes be accommodated by varying the size of the workforce? Should part-timers be used, or should overtime and idle time absorb fluctuations? Should subcontractors be used on fluctuating orders so a stable workforce can be maintained? Should prices or other factors be changed to influence demand? Chris Schrage OPS 13 3 Chris Schrage OPS 13 4 Capacity options Changing inventory levels Varying workforce size by hiring/layoffs Varying production rates through overtime or idle time Subcontracting Using part-time workers options Influencing demand Back ordering during high-demand periods Counter-seasonal product and service mixing Chris Schrage OPS 13 Chris Schrage OPS

2 Mixing Options Chase strategy Hire & fire employees to meet demand levels Level strategy Maintain constant level of company employees Aggregate Planning Methods Graphical and Charting Method Transportation Method of Linear Programming Look for OPTIMAL solution Management Coefficients Use of heuristics Others LDR- optimum production rate and workforce size for specific period Simulation----OPSIM Chris Schrage OPS 13 7 Chris Schrage OPS 13 8 Graphical and Charting Method Easiest to Use Many solutions not choose optimal solution Chris Schrage OPS 13 9 Power s Ladder Manufacturing Expected Days Chris Schrage OPS per day Daily Expected Days Chris Schrage OPS per day Average requirement= 84/246 = 34 per day Chris Schrage OPS Average requirement= 84/246 = 34 per day 2

3 Cost Information Backorder (shortage) per ladder $1 per month carrying $3 per month Present work force- ladders/ month Cost is $ 7 per ladder at /mo. Cost is $7 for each ladder OVER /mo. If less than ladders/mo. Cost is $82 per ladder Constant workforce level 34 units/day forecast Change Chris Schrage OPS Chris Schrage OPS Calculations Additional Costs 34 units/day $3832 forecast units over per = $ Change $1, units $1/unit = $4,44 2 units $3 per unit = $646 Lenova Computer, Ltd Beginning inventory 1 units Stockout $ per unit Cost $1 per unit based on count at month s end Sub-contracting $4 extra per unit Maximum of 1 extra units per month Maximum of units per month $1 extra per unit 236 units Chris Schrage under OPS 13 per = $2832 Chris Schrage OPS Plan 1- Produce at /month and subcontract to meet demand Plan 2- produce at / month and use overtime to meet demand Plan 1 Beginning = 1 Plan 2a Beginning = 1 production +3 3 Subcontrator Total 3 + Total Chris Schrage OPS $ per unit stockout Chris Schrage OPS 13 3

4 Plan 2b Beginning = 1 Plan 3 Beginning = production + +1 Overti me Total Total Chris Schrage OPS Chris Schrage OPS 13 Plan comparison Transportation Model Plan Plan 1 Plan 2a Plan 2b Plan 3 Cost $, $, $12, $, Method of linear programming Attempts to find the optimal solution The Schedule-Sequencing Problem Edward H. Bowman Operations Research, Vol. 7, No. (Sep. - Oct., 199), pp Assembly-Line Balancing by Linear Programming E. H. Bowman Operations Research, Vol. 8, No. 3 ( - Jun., 196), pp Chris Schrage OPS 13 Chris Schrage OPS 13 Transportation Table Transportation Table Allocate production capacity to meet demand at a minimum. Assume the initial inventory has no holding in the initial period To From Excess Supply Initial Chris Schrage OPS Period Initial Regular-time /unit /unit Subcontract /unit Carrying /unit-month Subcontract 4 Chris Schrage OPS $1 $1 $ $4 Forecast 4 units 4

5 Results To From Excess Time Supply Initial DEMAND Total Cost $11,79 Chris Schrage OPS 13 2 Transportation Table Allocate production capacity to meet demand at a minimum. No initial or ending inventory. Period Regular Time Initial Regular-time /unit /unit Subcontract /unit Carrying /unit-month Subcontract units $98 $131 $1 $1 Forecast Chris Schrage OPS To To From Excess Time Supply DEMAND From Excess Time Supply Regular Time DEMAND ,67 3,11 327, 296,81 TOTAL 1,6,81 TOTAL Chris Schrage OPS Chris Schrage OPS Services Cost of labor is Critical Assure response to customer needs Allow for on-call resources Flexibility in skill base Personal flexibility for work scheduling Restaurants Smoothing production rate Appropriate workforce size Chris Schrage OPS Chris Schrage OPS 13 3

6 Small service industries Copyworks H&R Block Airline Industry Flights in and out Number of flights Number of passengers serviced Air and ground personnel Fare allocation Chris Schrage OPS Chris Schrage OPS Yield Management Revenue management Attempt to maximize profit (or yield) In response to perish-ability of service offerings Characteristics Can be sold in advance of consumption fluctuates Capacity if relatively fixed can be segmented Variable s low-fixed s high Yield management issues Multiple pricing structures Forecasts of use and duration of the use Changes in demand Chris Schrage OPS Chris Schrage OPS Yield Management Matrix Price Tend to be fixed Tend to be variable Duration of Use Predictable Unpredictable Quadrant 1 Movies Convention centers Quadrant 3 Restaurants Golf courses Quadrant 2 Hotels Airlines Quadrant 4 Nursing homes Rehabilitation centers Chris Schrage OPS